Dr. Ramírez-Arias, Guillermo

The presence of condensate inside the dryer cylinders of a paper machine produces a significant increase in the power required to accelerate the section, risking a drive overload and / or section shutdown. In previous works, the authors developed a robust estimation algorithm for the condensate power and a generalized correlation for the estimation of condensate loads in industrial dryer cylinders up to 55 [mm] of condensate rim. This paper presents and evaluates a rule-based expert system (ES) capable of detecting the presence and amount of condensate in up to three groups of cylinders with different condensate loads. The ES can give an early warning message to the operators, and determine the condensate load and number of cylinders within each group. Evaluation is done using a combined condensate load for a fictitious 1500-mm, 8 cylinder dryer section. Results show the capacity of the developed ES to give early warning, as well as a correct estimation of the condensate loads and numbers of cylinders involved.

Condensate accumulated inside dryer cylinders will produce an increased power demand and eventually the inability of the dryer drive to accelerate the section. In a previous paper, these authors presented an online estimation algorithm capable of detecting the presence of condensate during a section starting. In this paper, a complete set of tests is run over two experimental cylinders covering up to 40% of cylinder volumes, and the complete set of power curves are reported and analyzed. Specifically, the presence of a combined cascading-rimming region in the medium to high condensate loads is confirmed. This combined mode modifies the pattern followed by the maximum power in the low condensate region. Using these data, high-order and simplified correlations are proposed for the estimation of condensate in flooded dryer cylinders. These new correlations increase the capacity of the online estimation algorithm to give good estimations of the condensate load present inside the dryer cylinders up to 55 mm of rim thickness.